ECOLOGICAL MECHANISMS AND LANDSCAPE ECOLOGY

Landscape ecology deals with the effects of the spatial configuration of mosaics on a wide variety of ecological phenomena. Because problems in many areas of conservation biology and resource management are rel ated to landscape use, development of a rigorous theoretical and empir ical foundation for landscape ecology is essential. We present an appr oach to research that focuses on how individual-level mechanisms opera ting in a heterogeneous mosaic produce ecological patterns that are sp atially dependent. The theoretical framework that we develop considers the density and distribution of a population among patches as a funct ion of (a) within-patch movement patterns of individuals; (b) emigrati on from patches as a function of population density, patch configurati on, patch context, and within-patch movement; and (c) loss of individu als as they disperse through landscape elements. This theoretical fram ework is coupled with an empirical approach that emphasizes the use of experimental model systems (EMS), small-scale systems occupying ''mic rolandscapes.'' Such systems are amenable to experimental manipulation with adequate replication and control and may serve as analogs of sys tems occurring at broader landscape scales. where rigorous empirical w ork is more difficult. We illustrate the use of EMS with examples from our studies of beetles and ants in North America and of voles in Norw ay. Finally, we consider some factors that may constrain extrapolation s from EMS to other systems, scales, or levels. We believe that implem entation of a mechanistic approach to landscape ecology is essential t o deriving generalizations about how spatial heterogeneity influences ecological systems.